1. Field of the Disclosure
The present disclosure relates generally to apparatuses and methods for cementing downhole tubulars into a well bore, and more particularly, the present disclosure relates to a cementing manifold swivel.
2. Background Art
A well-known method of drilling hydrocarbon wells involves disposing a drill bit at the end of a drill string and rotating the drill string from the surface utilizing either a top drive unit or a rotary table set in the drilling rig floor. As drilling continues, progressively smaller diameter tubulars comprising casing and/or liner strings may be installed end-to-end to line the borehole wall. Thus, as the well is drilled deeper, each string is run through and secured to the lower end of the previous string to line the borehole wall. Then the string is cemented into place by flowing cement down the flowbore of the string and up the annulus formed by the string and the borehole wall.
To conduct the cementing operation, typically a cementing manifold is disposed between the top drive unit or rotary table and the drill string. Thus, due to its position in the drilling assembly, the cementing manifold must suspend the weight of the drill pipe, contain pressure, transmit torque, and allow unimpeded rotation of the drill string. When utilizing a top drive unit, a separate inlet is preferably provided at a swivel to connect the cement lines.
In operation, the cementing manifold and swivel allow fluids, such as drilling mud or cement, to flow therethrough while simultaneously enclosing and protecting from flow, a series of darts and/or spheres that are released on demand and in sequence to perform various operations downhole. Thus, as fluid flows through the cementing manifold, the darts and/or spheres are isolated from the fluid flow until they are ready for release.
Cementing manifolds and swivel assemblies are available in a variety of configurations; with the most common configuration comprising a sphere/single dart manifold. The sphere is dropped at a predetermined time during drilling to form a temporary seal or closure of the flowbore of the drill string, for example, or to actuate a downhole tool, such as a liner hanger, in advance of the cementing operation, for example. Once the cement has been pumped downhole, the dart is dropped to perform another operation, such as wiping cement from the inner wall of a string of downhole tubular members. One such manifold and swivel is described in U.S. Pat. No. 6,904,970 to Simson and U.S. Pat. No. 7,066,249 to Simson, both hereby incorporated herein by reference in their entireties.
In operation, the outer housing of the swivel is designed to remain stationary, while an inner mandrel rotates within the housing to enable a top drive unit to rotate the drill string. However, during liner running and cementing operations, conditions can occur wherein excessive amounts of torque are applied to the swivel assembly. It is important that the outer housing remain stationary and that excessive amounts of torque are not applied to the swivel so that cementing lines or other equipment does not fail. If such a failure were to occur, rig personnel would be exposed to high pressure, and high velocity fluids, which could result in personal injury or environmental damage.